.side-nav__brand {
  background: url('sinoiov.png') no-repeat left center !important;      #url括号内写的就是自己图片的名字，我这里的是logo.png
  margin-left: 12px;
  height: 34px;
  background-size: contain !important;
}
.side-nav__brand span{
    display: none;
}